1. Field of the Invention
The present invention relates generally to multiplexers and more specifically to multiplexers for providing an appropriately multiplexed stream and for use in the case where a plurality of coded data of moving pictures, audios, etc. are recorded on a recording media such as a disc or transmitted onto a transmission line.
2. Description of the Prior Art
If data generated every moment in a data source is to be transmitted to a device consuming the generated data so that the generated data (time series data) is exactly reproduced in the consuming device, the generated data has to be supplied to the consuming device so as not to overflow or underflow an input buffer of the consuming device. However, the generated data, which is a kind of time series data, may have to be transmitted intermittently, for example, in some bursts every frame period for some reason such as a need of coding, say, moving pictures because of a limitation of the transmission rate.
Thus problems of overflow and/or underflow of the consuming device input buffer arise in multiplexing a plurality of such time series data supplied in a burst mode.
One solution for the overflow problem is to provide the consuming device with a buffer large enough to soak up the difference between the maximum possible rate of data supply to the buffer and the consuming rate. One solution for the underflow problem is, again, to provide the consuming device with a buffer large enough to store an amount of data which will not be exhausted even in the longest intervals between data supplies. However, these solutions require buffers of a large capacity resulting in an increase in the cost. In particular, the latter solution is achieved by delaying the consumption of the time series data, causing another problem in operating the whole system.
Another solution for the above problems is to provide, in the preceding stage of a multiplexer in a transmitter, a system for converting a burst mode input into a constant rate input. If such systems are used for many inputs of various input rates, it is necessary to generate clocks of various frequencies, which increases the cost.
It is therefore an object of the invention to provide a method and a system for multiplexing a plurality of time series data supplied in burst modes without causing any overflow or underflow in a input buffer of the consuming device.